DESCRIPTION (As Adapted From the Investigator's Abstract): This proposal addresses novel therapeutic approaches to treat osteosarcoma (OS), utilizing a mouse model and translating the findings to clinical trials. Specifically, the investigator proposes to use aerosolized delivery of liposomal 9-nitro-camptothecin and gene therapy (intranasal) using IL-12 delivered as an adenovirus vector or polyethyleneimine. These studies will be carried out in a nude mouse model with injection of a metastatic subline of SAOS. Studies of efficacy will include survival, tumor nodule number and size, and histological evaluation of vessel ingrowth and expression of IL-12. Clinical trials will consist of a phase I trial of aerosolized liposomal 9-nitro-camptothecin in which patients with relapsed OS will be enrolled. An additional aim of the proposal is to look at the role of Fas expression in the metastatic potential of LM6 cells and to determine if IL-12 affects Fas expression.